This invention generally relates to perfusion-type balloon dilatation catheters used in percutaneous transluminal coronary angioplasty (PTCA).
PTCA is a widely used procedure for the treatment of coronary heart disease. In this procedure, a balloon dilatation catheter is advanced into the patient's coronary artery and the balloon on the catheter is inflated within the stenotic region of the patient's artery to open up the arterial passageway and increase the flow of blood through the artery. To facilitate the advancement of the dilatation catheter into the patient's coronary artery, a guiding catheter having a preshaped distal tip is first percutaneously introduced into the cardiovascular system of a patient by the Seldinger technique through the brachial or femoral arteries. The catheter is advanced until the preshaped distal tip of the guiding catheter is disposed within the aorta adjacent the ostium of the desired coronary artery. The guiding catheter is twisted or torqued from the proximal end, which extends out of the patient, to guide the distal tip of the guiding catheter into the ostium. A balloon dilatation catheter may then be advanced through the guiding catheter into the patient's coronary artery until the balloon on the catheter is disposed within the stenotic region of the patient's artery where it is inflated to open up the arterial passageway.
The perfusion-type dilatation catheter for angioplasty was introduced into the marketplace by Advanced Cardiovascular Systems, Inc.(ACS). This catheter, which can take the form of an over-the-wire, a fixed-wire or a rapid exchange type catheter, has one or more perfusion ports proximal and one or more perfusion ports distal to the dilatation balloon which are in fluid communication with a guidewire receiving inner lumen extending to the distal end of the catheter. When the balloon is inflated to dilate a stenosis, oxygenated blood in the artery or the aorta, or both, depending upon the location of the dilatation catheter within the coronary anatomy, is forced to pass through the proximal perfusion ports, through the inner lumen of the catheter and out the distal perfusion ports. The catheter provides oxygenated blood downstream from the inflated balloon which in turn prevents or minimizes ischemic conditions in tissue distal to the catheter. The perfusion of blood distal to the inflated balloon allows for long term dilatations, e.g. 30 minutes or even several hours or more. Commercially available perfusion-type dilatation catheters, which have been highly praised by the medical profession and which have met with much commercial success, include the STACK PERFUSION.RTM. Dilatation Catheter which is sold by ACS.
When using an over-the-wire version of a perfusion-type dilatation catheter, a guidewire is usually inserted into an inner lumen of the dilatation catheter before it is introduced into the patient's vascular system and then both are introduced into and advanced through the guiding catheter to its distal tip seated within the ostium of the desired coronary artery. The guidewire is first advanced out of the seated distal tip of the guiding catheter into the desired coronary artery until the distal end of the guidewire extends beyond the lesion which is to be dilatated. The dilatation catheter is then advanced out of the distal tip of the guiding catheter into the patient's coronary artery, over the previously advanced guidewire, until the balloon on the distal extremity of the dilatation catheter is properly positioned across the lesion to be dilatated. Once properly positioned across the stenosis, the balloon is inflated to a predetermined size with radiopaque liquid at relatively high pressures (e.g., generally 4-12 atmospheres), usually for extended periods, to dilate the stenosed region of a diseased artery. After the inflation, the balloon is finally deflated so that the dilatation catheter can be removed from the dilated stenosis to resume blood flow.
The rapid exchange version of the perfusion-type dilatation catheter has a short guidewire receiving sleeve or inner lumen extending through a distal portion of the catheter. The sleeve or inner lumen extends proximally from a first guidewire port in the distal end of the catheter to a second guidewire port in the catheter spaced proximally from the inflatable member of the catheter. Perfusion ports are provided proximal and distal to the inflatable member or balloon which are in fluid communication with the short guidewire receiving sleeve or inner lumen. A slit may be provided in the wall of the catheter body which extends distally from the second guidewire port, preferably to a location proximal to the location of the balloon. The structure of the catheter allows for the rapid exchange of the catheter without the need for an exchange wire or adding a guidewire extension to the proximal end of the guidewire.
The rapid exchange type perfusion catheter was introduced by ACS under the trademark the ACS RX PERFUSION.RTM. Coronary Dilatation Catheter. This catheter has likewise been widely praised by the medical profession and it has met with much success in the marketplace because of the advantages of its unique design. The rapid exchange features of this catheter are described and claimed in U.S. Pat. No. 5,040,548 (Yock), U.S. Pat. No. 5,061,273 (Yock) and U.S. Pat. No. 4,748,982 (Horzewski et al.) which are incorporated herein by reference.
One of the problems encountered with perfusion-type catheters is that when a guidewire is advanced within the guidewire lumen of the catheter, the guidewire may occasionally pass through a perfusion-port in the catheter shaft. This has become more common as the guidewire diameters have become smaller. Such guidewire excursions through the perfusion ports are not desireable because they interfere with the angioplasty procedure. In such a case the guidewire has to be withdrawn proximally to disengage the guidewire from the perfusion port and then advanced through the catheter lumen. If the guidewire excursion deformed the distal tip of the guidewire, the guidewire may have to be completely withdrawn from the patient so that the distal tip can be reshaped and then readvanced through the catheter shaft. When a guidewire passes out one of the perfusion ports, it may traumatically engage the blood vessel wall. Additionally, as catheter profiles are reduced, the more difficult it is to provided adequate blood flow distal to the balloon to avoid ischemic conditions. What has been needed and previously unavailable is an easily manufactured perfusion-type catheter which will reduce the incidence of a guidewire passing through a perfusion port when the guidewire is advanced through the guidewire lumen and provide effective blood flow through the perfusion ports to ensure adequate blood flow distal to the balloon when the balloon is inflated. The present invention satisfies these and other needs.